Someone who can afford not to be a scally.. They go to decent shops to buy their clothes, such as Burton, or Topman, and pride themselves on their general appearance and the fact they will get a job that pays better than the scum that hangs around MCDonalds either being annoying and picking fights, or just working there.

Word used by 'alternative' types to further shield themselves from the forbidden mainstream and put more barriers between themselves and the rest of the world.
Initially developed out of spite due to the likely verbal and physical attacks from 'chavs' or inebriated followers of mainstream activity, the term now seems to be applied with a sense of pride, to the extent of labelling and in some cases returning the verbal and physical abuse to the supposed 'trendy'.
The obvious irony in this statement is that, as is aforementioned, a select niche of society (namely, the alternative society)use this phrase almost exclusively (at least in this context) and yet they use it to somehow proclaim their individuality.
The truth, it would seem, is that it is an excuse. A way of excusing the fact that the populous don't like the way you look and the way you dress. They have their own reasons i'm sure, some well-founded, some slightly bigotted but still individual reasons that aren't incited by the media (no 'freak-bashing' music videos on MTV for example, or articles about how wrong dyeing your hair blue in the National Press). Due to this seemingly unanimous disapproval, this term is used to imply that the offending party doesn't like them because they are a trendy, and the accusing party is so out-there and hip and open-minded that the spoon-fed, publicised masses simply couldn't understand.
An element of denial is involed as well, the subculture referred to earlier has been created out of a need ot be accepted. The majority of the users of this term have not been accepted generally by their peers and seek others to share this feeling. The numbers rise and rise and before you know it, we have a group large enough to huddle together in there issues with other people and shield themselves from it with boundaries, borders, narrow-mindedness and phrases such as this.
They believe that they are doing what they do becuase they don't like what has been 'dealt' to them and are un-impressed with their peers, their government and their country in general, but that is a fantasy (too much Bad Religion can go to your head ;)). It is largely due to the fact that their extreme sense of dress WILL be accepted by a much smaller section of society, and therefore they can join the huddle. Rather like penguins.
In short, if you call someone a trendy and mean half of the emotive and spiteful definitions listed here, chances are you deserve to be treated with the same narrow-mindedness that you treat the rest of the world with.

Trendy males, Somebody who does not feel they need to define themselves with their music taste or fashion sense. They are nothing like Chavs or Towniesas they do not feel a hatred to all other styles (though can't say i am a personal fan of chavs or townies) and are in fact very open minded in this way. Generally middle class and will have a job too fund their way of life. They enjoy being with their friends and/or girlfriends. They are usually mature individuals who are in late education. They have no problem with socialising with any other groups and are usually peaceful people. Everybody is individual and trendys realise this and so do not feel a need to define themselves. Some may be a little too gregarious in believing they are good looking enough to play alont other females but most are just very outgoing individuals. Contrary to popular belief most do not just follow fashions but in fact are able to see if the style will suit them personally before buying. They are up to date on all the latest technology usually as they feel they as much as anyone else need a good way to listen to their music or contact their friends. Usually very vein people as they like to look the best they possibly can do.This is a UK definition not a clue about abroad. :)
Trendy girls, well thats just an entirely different definition, personally i avoid most of them.

Nick: What the Bloody hell are you wearing?
Tom: Its erm trendy??:S
Nick: You don't have a clue.